KR20220011771A - Uv light emitting device, light emitting device package and lighting device - Google Patents

Abstract

The present invention provides an UV light emitting device, a manufacturing method of the UV light emitting device, a light emitting device package, and a lighting device, wherein luminous intensity can be improved by improving crystal quality of a light emitting structure. The UV light emitting device comprises: a substrate; a first undoped GaN layer including a flat upper surface and a V fit on the substrate; a first nitride layer disposed on the V fit of the first undoped GaN layer; a first undoped AlGaN-based semiconductor layer disposed on the first undoped GaN layer of the first nitride layer; and a second undoped GaN layer located on the first undoped AlGaN-based semiconductor layer. The first undoped AlGaN-based semiconductor layer includes a first region located on a flat upper surface of the first undoped GaN layer, and a second region located on the V fit of the first undoped GaN layer. An AI composition of the first region may be greater than an AI composition of the second region.

Description

UV light emitting device, light emitting device package and lighting device

The embodiment relates to an ultraviolet light emitting device, a method for manufacturing an ultraviolet light emitting device, a light emitting device package, and a lighting device.

A light emitting device (Light Emitting Device) can be produced by combining a pn junction diode with a characteristic in which electric energy is converted into light energy, a group 3-5 element or a group 2-6 element on the periodic table, and the composition ratio of the compound semiconductor is Various colors can be realized by adjusting.

Nitride semiconductors are receiving great attention in the field of developing optical devices and high-power electronic devices due to their high thermal stability and wide bandgap energy. In particular, ultraviolet (UV) light-emitting devices, blue light-emitting devices, green light-emitting devices, and red light-emitting devices using nitride semiconductors have been commercialized and widely used.

The ultraviolet light emitting device (UV LED) is a light emitting device that emits light in a wavelength range of 200 nm to 400 nm. The ultraviolet light emitting device is composed of a short wavelength and a long wavelength depending on the use. The short wavelength may be used for sterilization or purification, and the long wavelength may be used for an exposure machine or a curing machine.

On the other hand, the ultraviolet light emitting device has a problem in that light acquisition efficiency and light output are inferior compared to the blue light emitting device. This is acting as a barrier to the practical use of the ultraviolet light emitting device.

For example, a group III nitride used in an ultraviolet light emitting device can be widely used from visible light to ultraviolet light, but there is a problem in that the efficiency of ultraviolet light compared to visible light is lowered. The reason is that group III nitride absorbs ultraviolet rays as the wavelength of ultraviolet rays increases, and the internal quantum efficiency decreases due to low crystallinity.

Since the UV light emitting device has a low In composition, it is difficult to see the In localization effect in a quantum well compared to a blue LED. Therefore, in the prior art, the control and crystallinity of the threading dislocation rising from the lower layer affects the luminosity of the chip.

The embodiment may provide an ultraviolet light emitting device with improved luminosity according to the improvement of crystal quality, a method for manufacturing an ultraviolet light emitting device, a light emitting device package, and a lighting device.

In addition, the embodiment may provide an ultraviolet light emitting device with improved luminosity by improving defects, a method for manufacturing an ultraviolet light emitting device, a light emitting device package, and a lighting device.

An ultraviolet light emitting device according to an embodiment includes a substrate; a first undoped GaN layer comprising a V-pit having a top surface and a side surface on at least a portion of the substrate; a first nitride layer disposed on the V-pit of the first undoped GaN layer; a first undoped AlGaN-based semiconductor layer disposed on the first undoped GaN layer and the first nitride layer; and a second undoped GaN layer positioned on the first undoped AlGaN-based semiconductor layer, wherein the first undoped AlGaN-based semiconductor layer includes a first region positioned on an upper surface of the first undoped GaN layer; and a second region positioned on the V-pit of the first undoped GaN layer, wherein an Al concentration of the first region may be greater than an Al concentration of the second region.

The first undoped AlGaN-based semiconductor layer may have an Al composition of AlxGa1-xN (0.4≤Alx≤0.8).

The thickness of the first undoped AlGaN-based semiconductor layer may be 5 nm to 15 nm.

The thickness of the second undoped GaN layer may be 800 nm to 1500 nm.

At least two pairs of the first undoped AlGaN-based semiconductor layer and the second undoped GaN layer may be disposed on the first nitride layer.

The position of the upper surface of the first nitride layer may be lower than the position of the upper surface of the first undoped GaN layer.

the second undoped GaN layer includes a flat top surface and a V pit, and a second nitride layer disposed on the V pit of the second undoped GaN layer; a second undoped AlGaN-based semiconductor layer disposed on the second undoped GaN layer and the second nitride layer; and a third undoped GaN layer positioned on the second undoped AlGaN-based semiconductor layer, wherein the second undoped AlGaN-based semiconductor layer includes a third region positioned on an upper surface of the second undoped GaN layer; A fourth region positioned on the V-pit of the second undoped GaN layer may be included, and the Al concentration of the third region may be greater than the Al concentration of the fourth region.

The first nitride layer may include a silicon-based material.

The light emitting device package according to the embodiment may include the external light emitting device.

The embodiment can improve the luminous intensity of the ultraviolet light emitting device by improving the crystal quality of the light emitting structure.

In addition, the embodiment can improve the luminous intensity of the ultraviolet light emitting device by improving the defects of the light emitting structure.

1 is a cross-sectional view illustrating an ultraviolet light emitting device according to an embodiment.
FIG. 2 is a cross-sectional view illustrating the degree of defects of the ultraviolet light emitting device including the undoped AlGaN-based semiconductor layer of FIG. 1 .
3 to 7 are cross-sectional views illustrating a method of manufacturing an ultraviolet light emitting device according to an exemplary embodiment.
8 is a cross-sectional view illustrating an ultraviolet light emitting device according to another embodiment.
9A and 9B are TD Density comparison photographs of Comparative Examples and Experimental Examples.
10 is a cross-sectional view illustrating a light emitting device package according to an embodiment.

In the description of embodiments, each layer (film), region, pattern or structure is “on/over” or “under” the substrate, each layer (film), region, pad or pattern. In the case of being described as being formed on, “on/over” and “under” include both “directly” or “indirectly” formed through another layer. do. In addition, the reference for the upper / upper or lower of each layer will be described with reference to the drawings.

FIG. 1 is a cross-sectional view illustrating an ultraviolet light emitting device according to an embodiment, and FIG. 2 is a cross-sectional view illustrating a defect degree of the ultraviolet light emitting device including the undoped AlGaN-based semiconductor layer of FIG. 1 .

1 and 2, the ultraviolet light emitting device 100 includes a first undoped GaN layer 106a, a nitride layer 107, an undoped AlGaN-based semiconductor layer 108, and a second undoped GaN layer. (106b) may be included.

The first undoped GaN layer 106a may be disposed on the substrate 105 . The first undoped GaN layer 106a may be at least one. For example, the first undoped GaN layer 106a may be a plurality of layers of two or more. The first undoped GaN layer 106a may have a plurality of V pits (V) by controlling a growth temperature or a growth pressure. For example, the first undoped GaN layer 106a may reduce the mobility of Ga by controlling a growth temperature or a growth pressure, and thus the first undoped GaN layer 106a including roughness. ) can be formed. For example, at least a portion of the first undoped GaN layer 106a may be formed to have a side surface or an upper surface, and the side surfaces may be formed to include a plurality of V pits (V). The roughness may be formed regularly or irregularly, but is not limited thereto.

The nitride layer 107 may be located in the V pit V. The nitride layer 107 may be formed at the lower end of the V pit (V). The nitride layer 107 may include, but is not limited to, SiNx (x>0). The nitride layer 107 is formed in the V pit (V) of the first undoped GaN layer 106a to improve defects occurring at the lower end of the V pit (V). For example, the nitride layer 107 is formed of an amorphous material and is formed at the lower end of the V pit (V) of the first undoped GaN layer 106a so that a dislocation occurring at the lower end of the V pit (V) is prevented from occurring in the first undoped GaN layer 106a. 2 It is possible to reduce propagation to the undoped GaN layer 106b and bend a path through which the defect propagates. The nitride layer 107 may be located on the upper surface formed on the first undoped GaN layer 106a in addition to the bottom of the V pit V, but is not limited thereto.

The undoped AlGaN-based semiconductor layer 108 may be disposed on the nitride layer 107 . The undoped AlGaN-based semiconductor layer 108 may be in direct contact with the nitride layer 107 . The undoped AlGaN-based semiconductor layer 108 may be grown on an upper surface and a side surface (V-pit side) of the first undoped GaN layer 106a. The undoped AlGaN-based semiconductor layer 108 includes a first region 108a positioned on an upper surface of the first undoped GaN layer 106a and a V fit (V) of the first undoped GaN layer 106a. It may include a second region 108b positioned thereon. The growth rate of the undoped AlGaN-based semiconductor layer 108 may be slower in the first region 108a than in the second region 108b. Accordingly, the Al concentration of the undoped AlGaN-based semiconductor layer 108 may be greater in the first region 108a than in the second region 108b. That is, since the Al concentration of the first region 108a is greater than that of the second region 108b, the binding energy of AlGaN in the first region 108a is greater than that of the second region 108b, which results in a V fit (V). Defects propagating from the lower end of , are bent to the second region 108b rather than the first region 108a, so that defects propagating to the second undoped GaN layer 106b can be reduced.

The undoped AlGaN-based semiconductor layer 108 may include a semiconductor material having a composition formula _{of Al x} Ga _{1-x N (0.4≤x≤0.8).} When the Al composition (x) of the undoped AlGaN-based semiconductor layer 108 is less than 0.4, dislocation blocking of the first region 108a may be reduced. When the Al composition (x) of the undoped AlGaN-based semiconductor layer 108 is greater than 0.8, a dislocation bending effect of the second region 108b may be reduced.

The thickness of the undoped AlGaN-based semiconductor layer 108 may be 50 nm or more. For example, the thickness of the undoped AlGaN-based semiconductor layer 108 may be 5 nm to 15 nm. When the thickness of the undoped AlGaN-based semiconductor layer 108 is less than 5 nm, the defect blocking effect of the first region 108a may be reduced and the defect bending effect of the second region 108b may be reduced. . When the thickness of the undoped AlGaN-based semiconductor layer 108 is greater than 15 nm, crystallinity may be deteriorated due to a lattice constant difference due to a high composition.

The second undoped GaN layer 106b may be disposed on the undoped AlGaN-based semiconductor layer 108 . The thickness of the second undoped GaN layer 106b may be 800 nm or more. For example, the thickness of the second undoped GaN layer 106b may be 800 nm to 1500 nm. When the thickness of the second undoped GaN layer 106b is less than 800 nm, the defect bending effect may be reduced.

The ultraviolet light emitting device 100 of the embodiment may include a light emitting structure 110 . The light emitting structure 110 may be positioned on the second undoped GaN layer 106b. The light emitting structure 110 may directly contact the second undoped GaN layer 106b.

The light emitting structure 110 may include a first conductivity-type AlGaN-based semiconductor layer 112 , an active layer 114 , and a second conductivity-type AlGaN-based semiconductor layer 116 .

The first conductivity-type AlGaN-based semiconductor layer 112 may be implemented with a semiconductor compound, for example, a compound semiconductor such as Group III-5 or Group II-6, and may be doped with a first conductivity-type dopant. For example, the first conductivity type AlGaN-based semiconductor layer 112 may include a semiconductor material having a composition formula _{of Al n} Ga _{1-n N (0≤n≤1).} When the first conductivity-type AlGaN-based semiconductor layer 112 is an n-type semiconductor layer, the n-type dopant may include Si, Ge, Sn, Se, and Te, but is not limited thereto.

The active layer 114 may be formed of at least one of a single quantum well structure, a multi quantum well (MQW) structure, a quantum-wire structure, or a quantum dot structure.

The active layer 114 includes electrons (or holes) injected through the first conductivity-type AlGaN-based semiconductor layer 112 and holes (or electrons) injected through the second conductivity-type AlGaN-based semiconductor layer 116 . It is a layer that meets each other and emits light due to a difference in a band gap of an energy band according to a material forming the active layer 114 .

The active layer 114 may be formed of a compound semiconductor. The active layer 114 may be implemented, for example, by at least one of a group II-IV group and a group III-V compound semiconductor.

The active layer 114 may include a quantum well and a quantum wall. When the active layer 114 has a multi-quantum well structure, quantum wells and quantum walls may be alternately disposed. The quantum well and the quantum wall may be each _{formed of a semiconductor material having a compositional formula of In x} Al _y Ga _1-xy (0≤x≤1, 0≤y≤1, 0≤x+y≤1), or AlGaN /GaN, AlGaN/AlGaN, InGaN/GaN, InGaN/InGaN, InAlGaN/GaN, GaAs/AlGaAs, InGaAs/AlGaAs, GaP/AlGaP, InGaP AlGaP may be formed in any one or more pair structure, but is not limited thereto.

The second conductivity-type AlGaN-based semiconductor layer 116 may be implemented with a semiconductor compound, for example, a compound semiconductor such as Group III-5 or Group II-6, and may be doped with a second conductivity-type dopant. For example, the second conductivity type AlGaN-based semiconductor layer 116 may include a semiconductor material having a composition formula _{of Al p} Ga _{1-p N (0≤p≤1).} When the second conductivity-type AlGaN-based semiconductor layer 116 is a p-type semiconductor layer, the second conductivity-type dopant is a p-type dopant and may include Mg, Zn, Ca, Sr, Ba, or the like.

Although the first conductivity-type AlGaN-based semiconductor layer 112 is described as an n-type semiconductor layer and the second conductivity-type AlGaN-based semiconductor layer 116 as a p-type semiconductor layer, the first conductivity-type AlGaN-based semiconductor layer ( 112) may be formed as a p-type semiconductor layer, and the second conductivity type AlGaN-based semiconductor layer 116 may be formed as an n-type semiconductor layer, but is not limited thereto. A semiconductor having a polarity opposite to that of the second conductivity type, for example, an n-type semiconductor layer (not shown) may be formed on the second conductivity type AlGaN-based semiconductor layer 116 . Accordingly, the light emitting structure 110 may be implemented as any one of an n-p junction structure, a p-n junction structure, an n-p-n junction structure, and a p-n-p junction structure.

Although the light emitting structure 110 of the embodiment is described as the first conductivity type AlGaN-based semiconductor layer 112 and the second conductivity type AlGaN-based semiconductor layer 116 , the first conductivity type GaN-based semiconductor layer and the second conductivity type It may be formed of a GaN-based semiconductor layer, but is not limited thereto.

The ultraviolet light emitting device 100 of the embodiment may include a light-transmitting electrode layer 120 and first and second electrodes 151 and 153 .

The light-transmitting electrode layer 120 may be positioned on the second conductivity-type AlGaN-based semiconductor layer 116 . The light-transmitting electrode layer 120 may include an ohmic layer (not shown).

The first electrode 151 may be positioned on the first conductivity type AlGaN-based semiconductor layer 112 .

The second electrode 153 may be positioned on the second conductivity-type AlGaN-based semiconductor layer 116 .

A light extraction pattern such as roughness may be formed on the second conductivity-type AlGaN-based semiconductor layer 116 and the light-transmitting electrode layer 120 , but is not limited thereto.

The ultraviolet light emitting device 100 of an embodiment is in contact with the nitride layer 107 and the light emitting structure 110 is formed by the undoped AlGaN semiconductor layer 108 formed on the first undoped GaN layer 106a. The crystallinity of the second undoped GaN layer 106b positioned below may be improved, and defects may be improved.

Referring to FIG. 2 , the ultraviolet light emitting device 100 according to an embodiment includes a first region 108a of an undoped AlGaN-based semiconductor layer 108 positioned on the upper surface of the first undoped GaN layer 106a, and the first region 108a. 1 may include a second region 108b of the undoped AlGaN-based semiconductor layer 108 positioned at the V-pit (V) of the undoped GaN layer 106a. The growth rate of the undoped AlGaN-based semiconductor layer 108 may be slower in the first region 108a than in the second region 108b. Accordingly, the Al concentration of the undoped AlGaN-based semiconductor layer 108 may be higher in the first region 108a than in the second region 108b. That is, since the Al concentration of the first region 108a is greater than that of the second region 108b, the binding energy of AlGaN in the first region 108a is greater than that of the second region 108b, which results in a V fit (V). Defects propagating from the lower end of the layer are bent to the second region 108b rather than the first region 108a, so that propagation to the second undoped GaN layer 106b can be reduced.

The UV light emitting device 100 according to an embodiment is not limited to a horizontal type, and may be applied to a vertical type UV light emitting device.

3 to 7 are cross-sectional views illustrating a method of manufacturing an ultraviolet light emitting device according to an exemplary embodiment.

Referring to FIG. 3 , the first undoped GaN layer 106a may be formed on the substrate 105 .

The substrate 105 may be formed of a material having excellent thermal conductivity, and may be a conductive substrate or an insulating substrate. For example, the substrate 105 may include at least one _{of sapphire (Al 2} O ₃ ), SiC, Si, GaAs, GaN, ZnO, GaP, InP, Ge, and Ga ₂ 0 _{3 .} A concave-convex structure may be formed on the substrate 105 , but the present invention is not limited thereto.

The first undoped GaN layer 106a may be at least one. That is, the first undoped GaN layer 106a may include two or more layers. The first undoped GaN layer 106a may include a plurality of V pits V by controlling a growth temperature or a growth pressure. For example, in the first undoped GaN layer 106a, the mobility of Ga may be reduced by adjusting the growth temperature or growth pressure, and thus the first undoped GaN layer 106a including roughness may be formed. can For example, at least a portion of the first undoped GaN layer 106a may be formed to have a side surface and an upper surface, and the side surfaces may be formed to include a plurality of V pits (V). For example, the roughness may be formed regularly or irregularly, but is not limited thereto.

Referring to FIG. 4 , a nitride layer 107 may be formed on the first undoped GaN layer 106a. The nitride layer 107 may be located in the V pit V. The nitride layer 107 may be formed at the lower end of the V pit V. The nitride layer 107 may include, but is not limited to, SiNx (x>0). The nitride layer 107 may be disposed in the V pit (V) of the first undoped GaN layer 106a to block defects occurring at the lower end of the V pit (V). For example, the nitride layer 107 is formed of an amorphous material and is formed at the lower end of the V pit (V) of the first undoped GaN layer 106a so that defects occurring at the lower end of the V pit are formed in the second undoped GaN layer ( 106b) can be reduced, and the path through which the defect propagates can be bent. The nitride layer 107 may be located on the upper surface formed on the first undoped GaN layer 106a in addition to the bottom of the V pit V, but is not limited thereto.

Referring to FIG. 5 , an undoped AlGaN-based semiconductor layer 108 may be disposed on the first undoped GaN layer 106a and the nitride layer 107 . The undoped AlGaN-based semiconductor layer 108 may be in direct contact with the nitride layer 107 . The undoped AlGaN-based semiconductor layer 108 may be grown on the upper surface of the first undoped GaN layer 106a and the side of the V pit (V). The undoped AlGaN-based semiconductor layer 108 includes a first region 108a positioned on an upper surface of the first undoped GaN layer 106a and a V fit (V) of the first undoped GaN layer 106a. It may include a second region 108b positioned thereon.

The growth rate of the undoped AlGaN-based semiconductor layer 108 may be slower in the first region 108a than in the second region 108b. Accordingly, the Al concentration of the undoped AlGaN-based semiconductor layer 108 may be greater in the first region 108a than in the second region 108b. That is, since the Al concentration of the first region 108a is greater than that of the second region 108b, the binding energy of AlGaN in the first region 108a is greater than that of the second region 108b, which results in a V fit (V). Defects propagating from the lower end of , are bent to the second region 108b rather than the first region 108a, so that defects propagating to the second undoped GaN layer 106b can be reduced.

The undoped AlGaN-based semiconductor layer 108 may be filled with a top surface of the nitride layer 107 on the V-pit (V) side of the first undoped GaN layer 106a. Accordingly, the undoped AlGaN-based semiconductor layer 108 may cover the nitride layer 107 .

The undoped AlGaN-based semiconductor layer 108 may include a semiconductor material having a composition formula _{of Al x} Ga _{1-x N (0.4≤x≤0.8).} When the Al composition (x) of the undoped AlGaN-based semiconductor layer 108 is less than 0.4, the defect blocking effect of the first undoped AlGaN-based semiconductor layer 108 may be reduced. When the Al composition (x) of the undoped AlGaN-based semiconductor layer 108 is greater than 0.8, the defect bending effect of the first undoped AlGaN-based semiconductor layer 108 may be reduced.

The thickness of the undoped AlGaN-based semiconductor layer 108 may be 50 nm or more. For example, the thickness of the undoped AlGaN-based semiconductor layer 108 may be 5 nm to 15 nm. When the thickness of the undoped AlGaN-based semiconductor layer 108 is less than 5 nm, the defect blocking effect of the first undoped AlGaN-based semiconductor layer 108 may be reduced, and the second undoped AlGaN-based semiconductor layer ( 108), the defect bending effect may be degraded. When the thickness of the undoped AlGaN-based semiconductor layer 108 is greater than 15 nm, crystallinity may be deteriorated due to a lattice constant difference due to a high composition.

Referring to FIG. 6 , a second undoped GaN layer 106b may be grown on the undoped AlGaN-based semiconductor layer 108 . The second undoped GaN layer 106b may be formed on the top and side surfaces of the undoped AlGaN-based semiconductor layer 108 . For example, the thickness of the second undoped GaN layer 106b may be 800 nm or more. The thickness of the second undoped GaN layer 106b may be 800 nm to 1500 nm. When the thickness of the second undoped GaN layer 106b is less than 800 nm, the defect bending effect may be reduced.

Referring to FIG. 7 , the light emitting structure 110 may be formed on the second undoped GaN layer 106b. The light emitting structure 110 may include a first conductivity-type AlGaN-based semiconductor layer 112 , an active layer 114 , and a second conductivity-type AlGaN-based semiconductor layer 116 .

The first conductivity-type AlGaN-based semiconductor layer 112 may be implemented with a semiconductor compound, for example, a compound semiconductor such as Group III-5 or Group II-6, and may be doped with a first conductivity-type dopant. For example, the second conductivity type AlGaN-based semiconductor layer 112 may include a semiconductor material having a composition formula _{of Al n} Ga _{1-n N (0≤n≤1).} When the first conductivity-type AlGaN-based semiconductor layer 112 is an n-type semiconductor layer, the n-type dopant may include Si, Ge, Sn, Se, and Te, but is not limited thereto.

The active layer 114 may be formed of at least one of a single quantum well structure, a multi quantum well (MQW) structure, a quantum-wire structure, or a quantum dot structure.

The active layer 114 includes electrons (or holes) injected through the first conductivity-type AlGaN-based semiconductor layer 112 and holes (or electrons) injected through the second conductivity-type AlGaN-based semiconductor layer 116 . It is a layer that meets each other and emits light due to a difference in a band gap of an energy band according to a material forming the active layer 114 .

The active layer 114 may be formed of a compound semiconductor. The active layer 114 may be implemented, for example, by at least one of a group II-IV group and a group III-V compound semiconductor.

The active layer 114 may include a quantum well and a quantum wall. When the active layer 114 has a multi-quantum well structure, quantum wells and quantum walls may be alternately disposed. The quantum well and the quantum wall may be each _{formed of a semiconductor material having a compositional formula of In x} Al _y Ga _1-xy (0≤x≤1, 0≤y≤1, 0≤x+y≤1), or AlGaN /GaN, AlGaN/AlGaN, InGaN/GaN, InGaN/InGaN, InAlGaN/GaN, GaAs/AlGaAs, InGaAs/AlGaAs, GaP/AlGaP, InGaP AlGaP may be formed in any one or more pair structure, but is not limited thereto.

The second conductivity-type AlGaN-based semiconductor layer 116 may be implemented with a semiconductor compound, for example, a compound semiconductor such as Group III-5 or Group II-6, and may be doped with a second conductivity-type dopant. For example, the second conductivity type AlGaN-based semiconductor layer 116 may include a semiconductor material having a composition formula _{of Al p} Ga _{1-p N (0≤p≤1).} When the second conductivity-type AlGaN-based semiconductor layer 116 is a p-type semiconductor layer, the second conductivity-type dopant is a p-type dopant and may include Mg, Zn, Ca, Sr, Ba, or the like.

The first conductivity-type AlGaN-based semiconductor layer 112 may be formed as a p-type semiconductor layer, and the second conductivity-type AlGaN-based semiconductor layer 116 may be formed as an n-type semiconductor layer, but is not limited thereto.

The ultraviolet light emitting device of the embodiment may include a light-transmitting electrode layer 120 and first and second electrodes 151 and 154 formed on the light emitting structure 110 .

The light-transmitting electrode layer 120 may be formed on the second conductivity-type AlGaN-based semiconductor layer 116 . The light-transmitting electrode layer 120 may include an ohmic layer (not shown), and may be formed by stacking a single metal, a metal alloy, or a metal oxide in multiple layers to efficiently inject holes.

For example, the light-transmitting electrode layer 120 may be formed of an excellent material that is in electrical contact with a semiconductor. For example, the light-transmitting electrode layer 120 may include indium tin oxide (ITO), indium zinc oxide (IZO), indium zinc tin oxide (IZTO), indium aluminum zinc oxide (IAZO), indium gallium zinc oxide (IGZO), or IGTO. (indium gallium tin oxide), AZO (aluminum zinc oxide), ATO (antimony tin oxide), GZO (gallium zinc oxide), IZON (IZO Nitride), AGZO (Al-Ga ZnO), IGZO (In-Ga ZnO), ZnO, IrOx, RuOx, NiO, RuOx/ITO, Ni/IrOx/Au, and Ni/IrOx/Au/ITO, Ag, Ni, Cr, Ti, Al, Rh, Pd, Ir, Ru, Mg, Zn, Pt , Au, may be formed to include at least one of Hf, but is not limited thereto.

A light extraction pattern may be formed on the second conductivity-type AlGaN-based semiconductor layer 116 and the light-transmitting electrode layer 120 , but is not limited thereto.

The first electrode 151 may be formed on the first conductivity-type AlGaN-based semiconductor layer 112 exposed from the active layer 114 and the second conductivity-type AlGaN-based semiconductor layer 116 , and the second electrode ( 153 ) may be formed on the light-transmitting electrode layer 120 .

The first electrode 151 or the second electrode 153 may include titanium (Ti), chromium (Cr), nickel (Ni), aluminum (Al), platinum (Pt), gold (Au), tungsten (W), At least one of molybdenum (Mo) may be formed as a single layer or a multilayer, but is not limited thereto.

8 is a cross-sectional view illustrating an ultraviolet light emitting device according to another embodiment.

As shown in FIG. 8 , the UV light emitting device according to another embodiment may employ the technical characteristics of the UV light emitting device according to the exemplary embodiment of FIG. 1 .

An ultraviolet light emitting device according to another embodiment includes a first undoped GaN layer 106a, a first nitride layer 107a, a first undoped AlGaN-based semiconductor layer 108, a second undoped GaN layer 106b, and a second undoped GaN layer 106b. It may include a second nitride layer 107b, a second undoped AlGaN-based semiconductor layer 109, and a third undoped GaN layer 106c.

The first undoped GaN layer 106a, the first nitride layer 107a, the first undoped AlGaN-based semiconductor layer 108, and the second undoped GaN layer 106b including the V pit V1 are one A detailed description will be omitted with reference to the ultraviolet light emitting device according to the embodiment. However, the second undoped GaN layer 106b may include a V pit V2.

The second nitride layer 107b may be located in a V pit (V) of the second undoped GaN layer 106b. The second nitride layer 107b may be formed at a lower end of the V-pit V2 of the second undoped GaN layer 106b. The second nitride layer 107b may include, but is not limited to, SiNx (x>0). The second nitride layer 107b may be formed in the V-pit V2 of the second undoped GaN layer 106b to block defects occurring at the lower end of the V-pit V2. For example, the second nitride layer 107b is formed of an amorphous material, and is formed at the lower end of the V-pit V2 of the second undoped GaN layer 106b. Propagation to the undoped GaN layer 106c may be reduced, and a path through which the defect propagates may be bent. The second nitride layer 107b may be located on the upper surface formed on the second undoped GaN layer 106b in addition to the lower portion of the V-pit V2, but is not limited thereto.

The second undoped AlGaN-based semiconductor layer 109 may be disposed on the second nitride layer 107b. The second undoped AlGaN-based semiconductor layer 109 may be in direct contact with the second nitride layer 107b. The second undoped AlGaN-based semiconductor layer 109 may be grown on top and side surfaces (V-pit side) of the second undoped GaN layer 106b. The second undoped AlGaN-based semiconductor layer 109 includes a third region 109a formed on the upper surface of the second undoped GaN layer 106b and a V fit ( A fourth region 109b formed on V2 may be included. The growth rate of the second undoped AlGaN-based semiconductor layer 109 may be slower in the third region 109a than in the fourth region 109b. Accordingly, the Al concentration of the second undoped AlGaN-based semiconductor layer 109 may be higher in the third region 109a than in the fourth region 109b. That is, since the Al concentration of the third region 109a is greater than that of the fourth region 109b, the AlGaN binding energy of the third region 109a is greater than that of the fourth region 109b, which results in a V fit (V2). Defects propagating from the lower end of , are bent to the fourth region 109b rather than the third region 109a, so that defects propagating to the third undoped GaN layer 106c can be reduced.

The second undoped AlGaN-based semiconductor layer 109 may include a semiconductor material having a composition formula _{of Al y} Ga _{1-y N (0.4≤y≤0.8).} When the Al composition (y) of the second undoped AlGaN-based semiconductor layer 109 is less than 0.4, the defect blocking effect of the third region 109a may be reduced. When the Al composition (y) of the second undoped AlGaN-based semiconductor layer 109 is greater than 0.8, the defect bending effect of the fourth region 109b may be reduced.

The thickness of the second undoped AlGaN-based semiconductor layer 109 may be 50 nm or more. For example, the thickness of the second undoped AlGaN-based semiconductor layer 109 may be 5 nm to 15 nm. When the thickness of the second undoped AlGaN-based semiconductor layer 109 is less than 5 nm, the defect blocking effect of the third region 109a may be reduced, and the defect bending effect of the fourth region 109b may be reduced. can be When the thickness of the second undoped AlGaN-based semiconductor layer 109 is greater than 15 nm, crystallinity may be deteriorated due to a lattice constant difference due to a high composition.

The third undoped GaN layer 106c may be disposed on the second undoped AlGaN-based semiconductor layer 109 . The thickness of the third undoped GaN layer 106c may be 800 nm or more. For example, the thickness of the third undoped GaN layer 106c may be 800 nm to 1500 nm. When the thickness of the third undoped GaN layer 106c is less than 800 nm, the defect bending effect may be reduced.

In the ultraviolet light emitting device according to another embodiment, the second undoped AlGaN-based semiconductor layer 109 is positioned on the second undoped GaN layer 106b and the second nitride layer 107b to further improve crystallinity, , it is possible to improve defects passing through the first undoped AlGaN-based semiconductor layer 108 .

* In the ultraviolet light emitting device according to another embodiment, the first undoped AlGaN-based semiconductor layer 108 is positioned on the first nitride layer 107a, and the second undoped AlGaN-based semiconductor layer 109 is formed with the second nitride layer ( Although the structure located on the 107b is limited, the description is not limited thereto, and the first undoped AlGaN-based semiconductor layer 108 and the second undoped GaN layer 106b are formed on the first nitride layer 107a at least. Two or more pairs may be alternated, and at least two or more pairs of the second undoped AlGaN-based semiconductor layer 109 and the third undoped GaN layer 106c may be alternated on the second nitride layer 107b.

comparative example Experimental Example 1
(x=0.4, T:5nm) Experimental Example 2
(x=0.4, T:10nm) Experimental Example 3
(x=0.6, T:10nm) nAlGaN (002)
(center/edge) 158/169 154/159 145/148 120/129 nAlGaN (102)
(center/edge) 197/207 181/195 175/192 162/160

Table 1 shows a comparative example in which an undoped AlGaN-based semiconductor layer is not formed on an undoped GaN layer, and another embodiment of FIG. 8 including first and second undoped AlGaN-based semiconductor layers on an undoped GaN layer. It is data comparing the crystallinity and threading dislocation density (TDD) of Experimental Examples 1 to 3 to which the UV light emitting device is applied. Here, the crystallinity may be compared with a center region and an edge region of the wafer. In addition, XRD measurement is data obtained by measuring surfaces 002 and 102 of the AlGaN-based semiconductor layer of the first conductivity type. Experimental Example 1 is an Al composition (x) of 0.4 and first and second undoped surfaces having a thickness of 5 nm. Including an AlGaN-based semiconductor layer, Experimental Example 2 includes first and second undoped AlGaN-based semiconductor layers having an Al composition (x) of 0.4 and a thickness of 10 nm, and Experimental Example 3 includes an Al composition (x) of 0.6 ( x) and first and second undoped AlGaN-based semiconductor layers having a thickness of 10 nm.

It can be seen that in Experimental Examples 1 to 3, the XRD FWHM is lower than that of Comparative Examples, and thus the crystallinity is improved.

9A and 9B are TD Density comparison photographs of Comparative Examples and Experimental Examples.

The ultraviolet light emitting device has a lower indium (In) composition of the light emitting structure than the blue light emitting device, so it is difficult to see the In constraint effect. The ultraviolet light emitting device causes a decrease in luminous intensity due to non-radiative recombination around a threading dislocation (TD) of a lower layer of the light emitting structure. Therefore, in the ultraviolet light emitting device, the TD control and crystallinity of the light emitting structure and the lower layer of the light emitting structure may have a great effect on the luminance of the chip.

9A shows a TD of a comparative example in which an undoped AlGaN semiconductor layer is not formed on an undoped GaN layer but a first conductivity type AlGaN-based semiconductor layer is formed, and FIG. 9B is a first and second undoped AlGaN layer on the undoped GaN layer. The TD of an experimental example in which the first conductivity type AlGaN-based semiconductor layer is formed after the AlGaN-based semiconductor layer is formed is shown. In the embodiment, defects are bent by the undoped AlGaN-based semiconductor layer, so that TD can be significantly reduced. Accordingly, since the ultraviolet light emitting device of the embodiment has a low indium (In) composition, non-radiative recombination in TD can be reduced.

Therefore, in the embodiment, an undoped AlGaN-based semiconductor layer is formed on the nitride layer to reduce TD and improve crystallinity to improve chip luminosity compared to the comparative example.

The ultraviolet light emitting device according to the embodiment may have a structure in which a plurality of them are arrayed, and may be included in a light emitting device package. The ultraviolet light emitting device according to the embodiment may be used in various fields such as curing, sterilization, and special lighting depending on the wavelength.

The ultraviolet light emitting device according to the embodiment may be applied to a backlight unit, a lighting device, a display device, a vehicle display device, a smart unit, and the like, but is not limited thereto.

10 is a cross-sectional view illustrating a light emitting device package according to an embodiment.

The light emitting device package 200 according to the embodiment includes a package body part 205 , the first lead electrodes 213 and second lead electrodes 214 installed on the package body part 205 , and the package body part ( The UV light emitting device 100 installed in 205 and electrically connected to the first lead electrode 213 and the second lead electrode 214, and a molding member 230 surrounding the UV light emitting device 100 are provided. Included.

The first lead electrode 213 and the second lead electrode 214 are electrically isolated from each other, and serve to provide power to the ultraviolet light emitting device 100 . In addition, the first lead electrode 213 and the second lead electrode 214 may include a function of increasing light efficiency by reflecting the light emitted from the UV light emitting device 100, and the UV light emitting device ( 100) may include a function of discharging the generated heat to the outside.

The ultraviolet light emitting device 100 may be electrically connected to the first lead electrode 213 or the second lead electrode 214 by any one of a wire method, a flip chip method, or a die bonding method.

The ultraviolet light emitting device 100 may be an ultraviolet light emitting device according to an embodiment, but is not limited thereto, and may be an ultraviolet light emitting device according to another embodiment.

The molding member 230 may include a phosphor 232 to form a white light light emitting device package, but is not limited thereto.

The upper surface of the molding member 230 may be flat, concave, or convex, but is not limited thereto.

Features, structures, effects, etc. described in the above embodiments are included in at least one embodiment, and are not necessarily limited to only one embodiment. Furthermore, features, structures, effects, etc. illustrated in each embodiment can be combined or modified for other embodiments by those of ordinary skill in the art to which the embodiments belong. Accordingly, the contents related to such combinations and modifications should be interpreted as being included in the scope of the embodiments.

In the above, the embodiment has been mainly described, but this is only an example and does not limit the embodiment, and those of ordinary skill in the art to which the embodiment belongs are provided with several examples not illustrated above within the range that does not deviate from the essential characteristics of the embodiment. It can be seen that variations and applications of branches are possible. For example, each component specifically shown in the embodiment can be implemented by modification. And differences related to such modifications and applications should be construed as being included in the scope of the embodiments set forth in the appended claims.

105: substrate 106a: first undoped GaN layer
107: nitride layer 108: first undoped AlGaN-based semiconductor layer
106b: second undoped GaN layer 109: second undoped AlGaN-based semiconductor layer
106c: third undoped GaN layer

Claims (9)

Board;
a first undoped GaN layer comprising a V-pit having a top surface and a side surface on at least a portion of the substrate;
a first nitride layer disposed on the V-pit of the first undoped GaN layer;
a first undoped AlGaN-based semiconductor layer disposed on the first undoped GaN layer and the first nitride layer; and
a second undoped GaN layer positioned on the first undoped AlGaN-based semiconductor layer;
The first undoped AlGaN-based semiconductor layer includes a first region positioned on an upper surface of the first undoped GaN layer and a second region positioned on a V-pit of the first undoped GaN layer;
The Al concentration of the first region is greater than the Al concentration of the second region UV light emitting device.
According to claim 1,
The first undoped AlGaN-based semiconductor layer is AlxGa1-xN (0.4

An ultraviolet light emitting device having an Al composition of x≤0.8).
According to claim 1,
The first undoped AlGaN-based semiconductor layer has a thickness of 5 nm to 15 nm.
According to claim 1,
The second undoped GaN layer has a thickness of 800 nm to 1500 nm.
According to claim 1,
At least two pairs of the first undoped AlGaN-based semiconductor layer and the second undoped GaN layer are disposed on the first nitride layer.
According to claim 1,
The position of the upper surface of the first nitride layer is lower than the position of the upper surface of the first undoped GaN layer.
7. The method according to any one of claims 1 to 6,
The second undoped GaN layer includes a flat top surface and a V-pit,
a second nitride layer disposed on the V-pit of the second undoped GaN layer;
a second undoped AlGaN-based semiconductor layer disposed on the second undoped GaN layer and the second nitride layer; and
a third undoped GaN layer positioned on the second undoped AlGaN-based semiconductor layer;
The second undoped AlGaN-based semiconductor layer includes a third region positioned on the upper surface of the second undoped GaN layer and a fourth region positioned on the V-pit of the second undoped GaN layer;
The Al concentration of the third region is greater than the Al concentration of the fourth region UV light emitting device.
7. The method according to any one of claims 1 to 6,
The first nitride layer is an ultraviolet light emitting device including a silicon-based material.
A light emitting device package comprising the ultraviolet light emitting device of any one of claims 1 to 6.

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